In the related art, as a centrifugal blood pump used during cardiac surgery or after cardiac surgery, a disposable centrifugal blood pump in which only an impeller (vane wheel) which comes into contact with blood of a patient and a housing (pump housing) for storing the same are replaced is used.
Normally, in the disposable centrifugal blood pump of this type, the impeller is supported by a pivot bearing or a contact bearing protected by a mechanical seal. However, since the bearing is used without lubrication in order to avoid contamination of blood, it is subjected to intensive abrasion or friction, which leads to a problem of durability. There are also problems being pointed out such as plaque formation around the bearing or hemolysis caused by the bearing.
Therefore, the expiration date for use of these disposable parts is limited to about two days at maximum. However, replacement which has to be done every two days is actually heavy burden for patients and medical institution that need long-term auxiliary circulation.
In order to solve such problems, a disposable centrifugal blood pump with magnetic coupling employing a magnetic coupling which supports an impeller to be integrated in a centrifugal blood pump with a magnetic force in a non-contact manner has been proposed (see Non-Patent Documents 1 to 3).
The disposable centrifugal blood pumps with magnetic coupling disclosed in Non-Patent Documents 1 and 2 employ a cylindrical permanent magnet magnetized in the radial direction used as a rotor in the housing as in the case of a brushless DC motor, and the disposable centrifugal blood pump with magnetic coupling disclosed in Non-Patent Document 3 is configured in such a manner that the rotor is supported by magnetic coupling working between an electromagnet provided on the side of a stator around the outer periphery of the rotor and a permanent magnet provided on the rotor, and torque is transmitted to the rotor by magnetic coupling working between a plurality of permanent magnets provided on the inner surface of the rotor and a plurality of permanent magnets of a torque transmission disk disposed so as to oppose the permanent magnets.    Non-Patent Document 1: Reto Schob, Centrifugal pump without bearings or seals, World Pumps, July 2002.    Non-Patent Document 2: CentriMag Left Ventricular Assist System Catalogue, Levitronix.    Non-Patent Document 3: H. Hoshi, K. Kataoka, K. Ohuchi, J. Asama, T. Shinshi, A. Shimokohbe and S. Takatani, Magnetically Suspended Blood Pump with a Radial Magnetic Driver, ASAIO journal, pp. 60-64, (2005).